What defines the Gangster Genre?
The American gangster film genre is a subgenre of the wider crime film, and the genre is characterized by stories about gangs and organized crime. While the overwhelming popularity of the genre is a thing of the past(started in the 70s and ended in the late 90s,) many gangster productions have proved to be timeless in nature and a handful of them are even considered to be contenders for the greatest film ever made. There are still quality gangster films made today, time had no effect on writers' ability to create new stories, but numbers show that younger, as well as older audiences, are growing increasingly tired of gangster movies due to the prior abundance of them.
Content Conventions
A commonly repeated concept in the gangster genre is wealth and its ability to ruin people/ the people around whoever is wealthy. Usually, if the protagonist in a gangster movie is/becomes the wealthy one, they will not start out the same person they started out as at the beginning of the movie. To be more specific, a character who starts off as a good person with good connections with either family, friends, or business partners will likely destroy the good parts of themself through their wealth, and in other stories, the main character who starts off as a jerk due to their own wealth will go through an arc that will win them better relationships with the people around them.
Another common trend in gangster films is the influence of drugs. Whether it's the drugs that make the gangsters in the film their money or simply drugs they take to get through their day, drugs are usually a central element in gangster films. Drugs, as well as wealth's influence, drive characters to make certain decisions that usually push the plot forward and they usually tend to push characters the protagonist grow close to away.
Production Techniques
As for actual production techniques common in gangster films, an incredibly common similarity can be found in the first few scenes. Most (if not all) gangster films open up and show guns, money, and/or drugs, to give the viewer a sense of the gangster lifestyle right off the bat, and even more, the scenes usually take place in a dimly lit room. Certain choices at the beginning of gangster films are made to either invest viewers in the drug-centric societies or to establish a character's power or personality.
In gangster productions, the main characters(more often than not being members of an organized crime group or mafia) are wearing suits or expensive clothing. Since suits are associated with business, they give the viewer the sense that the characters are professionals or more simply "mean business." Even more, the non-gangster characters in the production will usually wear clothes that look cheap or poor-looking in comparison to further push the idea that the mafia has the money and the power.
Marketing
The target demographic for most gangster films is around 15-40 years old, and while gangster films can (naturally) be enjoyed by all genders, the core audience for films like these are males. Additionally, these males are usually from older generations; it's not incredibly common for younger people to be interested in gangster movies anymore. A possible reason for the popularity of these films with older audiences is that they grew up with movies in the genre and/or their parents grew up during a time where mafias actually existed in western society (the 1920s-1930s) and told them stories about them when they were young(and found it interesting later.)
Gangster film posters usually have the main characters with the most power in front of a black backdrop; the black symbolizes the darkness, criminality, and corruption in the life. Trailers for gangster movies usually glorify the main character, even if they are bad people, so the viewers can almost admire the character and identify with them.
Samples
GoodFellas
The Godfather
